Exosome-Transferred APOC3-Ncrna Complex Mediates Iron Regulation in Beta-Thalassemia Major

Background: Exosomes are small membrane vesicles (50-90 mm in diameter) containing bioactive proteins and genetic materials that may be transferred to accept cells, resulting in potent biological effects in the circulatory system. Exosome-transferred APOC3-ncRNA may be a crucial function in iron regulation. However, the role in β-thalassemia major is remains unclear.

Aim: The aim of this study was to investigate how Exosome-transferred APOC3-ncRNA adapts to iron regulation in β-thalassemia major.

Design: Using Proteomics, RNA-sequencing and lncRNA Q-PCR array, we demonstrated expression of exosomes-transferred APOC3-ncRNAs in plasma of β-thalassemia major patients (n = 40). Identification of exosome by Dynamic light scattering (DLS), Flow cytometry and western blots. Lentiviral infection, ncRNAs transfection and in vitro studies revealed that knockdown or overexpression obviously increased or ameliorated exosomes-induced iron regulation. Bioinformatics analysis, luciferase assay and in vitro studies revealed that ncRNAs functioned as a repressing mediator and formed a feedback loop with ncRNAs and target gene to mediate iron regulation.

Results: We observed that ncRNA is differential expressed in the exosomes of β-thalassemia major. We analyzed the effects of ex vivo-derived exosomes for iron regulation by monocytes/hepatocytes model. In vitro model showed that exosomes were internalized by THP-1/HuH-7 cells, and regulates the IRP1/FPN/HAMP. In turn, Exosome-transferred APOC3-ncRNA mediates inflammatory cytokine expression and iron regulation via p38/pAKT/TRAF6/NF-kB pathway. Knockdown of APOC3-ncRNA reversed IRP1/FPN/HAMP expression.

Conclusions: This is the first example of extracellular APOC3/ncRNA regulating gene expression via circulatory exosomes-transferred to accept cells. Increased Exosome-transferred APOC3-ncRNA expression is one of the key factors that might have contributed to abnormal iron regulation in β-thalassemia major patients.